Route: MapMyRide — Strava. The route starts at Bedwell Bayfront Park, which has parking for dozens of cars. It goes over Dumbarton Bridge, to Coyote Hills, forming a lollipop loopto return to Bedwell Bayfront Park. Different sections of this route offer different experiences:

(A) 1.7 miles along CA-84 from Bedwell Bayfront Park to Dumbarton Bridge. This section is actually a bike trail next to San Francisco Bay. With views of the bay in the north, this section is quite pleasant, except for traffic noise along CA-84.

(B) 5.5 miles along Dumbarton Bridge and Marshland Road. There is a bike trail on Dumbarton Bridge, separated from vehicular traffic by a thick concrete wall. Traffic noise is very high. But views of San Francisco Bay are spectacular. The ride along Marsland Road is also scenic, staying within a few feet of San Francisco Bay at all times.

(C) 2.6 Marshland Road → Left on Thornton Ave → continue over CA-84 to Paseo Padre Parkway → Left on Patterson Ranch Road to enter Coyote Hills Regional Park. Before Marshland meets Thornton, there is Don Edwards SF Bay Wildlife Refuge to the right. Just before Paseo Padre meets Patterson Ranch, there are gorgeous views of Coyote Hills in the west and a large, expansive valley in the east.

(D) 4.2 miles from Patterson Ranch Road → Left on Alameda Creek Trail till the end of Alameda Creek Trail. These sections have bike trails all along. Patterson Ranch Road is quite peaceful, weaving through marshlands and hills. The left turn for Alameda Creek Trail is easy to miss. So study the Trail Map (PDF) for Coyote Hills.

Alameda Creek Trail is exceptionally peaceful. Away from any traffic noise, with water on both sides. There are picnic tables at the end of this trail. At this point, it is possible to turn left and continue along an unpaved road with a hybrid or mountain bike, all the way to Marshland Road.

(E) 4.8 miles along Alameda Creek Trail → Right on Bayview Trail to reach Patterson Ranch Trail. The best section of this ride is along Bayview Trail, with gorgeous views of San Francisco Bay! This is a great spot for watching sunset.

(F) Finally, retrace your steps to return to Bedwell Bayfront Park.

Traffic: On a Saturday morning in April 2015, there was a fair amount of vehicular traffic along CA-84 and Dumbarton Bridge. There is a bike trail here, so we never share road with vehicles. However, traffic noise is significantly high, especially on the bridge. There was minimal traffic from Dumbarton Bridge to Patterson Road, which is the entrance to Coyote Hills Regional Park. Within the park, the ride was very pleasant, with almost no traffic.

Climbing: Very little. Flat route almost everywhere except for a small hill climb in Coyote Hills.

Bike Trails: Most of the route is along bike trails with no vehicular traffic. Even the section of this route from Bedwell Bayfront Park to Dumbarton Bridge has a bike trail that parallels CA-84. Dumbarton Bridge itself has a bike lane, separated from traffic by a thick concrete wall. The only section which lacks a bike trail is between Dumbarton Bridge and the entrance to Coyote Hills Regional Park via Patterson Road. These roads have comfortable bike lanes with light traffic. See photos.

Views: Gorgeous views of San Francisco Bay from Dumbarton Bridge and from Coyote Hills. The section of this route in Coyote Hills is exceptionally scenic! I also like the views of Coyote Hills to the left as we ride along Paseo Padre Parkway.

Water stops and restrooms? Only at Coyote Hills Regional Park.

Picnic tables? At several locations in Coyote Hills Regional Park and at the end of Alameda Creek Trail (where the paved bike trail ends; further progress is possible along an unpaved bike trail).

Good time to visit? Any time of the year except when it is too cold or raining.

Extensions:

When the bike trail along Dumbarton Bridge merges into Marshland Road, it is possible to ride along Marshland Road in the opposite direction to explore that area. This adds somewhere between one to two miles overall.

By adding the entire length of Alameda Creek Trail, the overal route becomes 45 miles long. Alameda Creek Trail is a dedicated bike trail adjoining Alameda Creek, which is full of water year round. Most of Alameda Creek Trail goes through the cities of Hayward and Fremont, with traffic noise and various buildings in near vicinity. The section near Coyote Hills is serene, with awesome views of San Francisco Bay.